Today's electrical devices are required to have high integration and high performance. Accordingly, some of the electrical elements are often have high temperatures. For example, an automatic document feeder (ADF) is developed to be used with a flatbed scanner. The ADF can automatically feed document sheets one by one to the flatbed scanner to be scanned. However, most of the ADFs are asked to have reduced volumes and increased document-feeding speeds. As a result, a lot of heat is generated by the elements such as the print circuit board of the ADF. Cooling elements made of aluminum or copper, etc . . . are often used to reduce the temperature. However, the cooling effects are limited. The effect of a cooling cream is also limited. Furthermore, the cooling cream must be coated on the surface of the high-temperature uniformly, otherwise many problems may happen.
A more efficient method is to use a fan to cool the high-temperature element. However, conventional fan is equipped with a motor. The additional motor will also generate heat to increase the temperature within the electrical device. Furthermore, the additional motor will increase the cost.
It is then attempted by the applicant to deal with the above-mentioned problems.